Simplicity key to diagnosing, treating vitreoretinal lymphoma

Primary vitreoretinal lymphoma (VRL), the most common and most aggressive intraocular lymphoma, is readily diagnosed by determining the interleukin (IL)-10:IL-6 ratio in the vitreous. Treatment with intraocular injections of methotrexate achieved a 100% response rate of the VRL, with rare recurrences, Jacob Pe’er, MD, said.

Primary VRL is mostly a high-grade B-cell lymphoma. The other less aggressive forms are primary choroidal lymphoma, typically a low-grade B-cell lymphoma; primary iridal lymphoma, a rare form characterized by either B cells or T cells; and secondary uveal lymphoma, he explained.

Primary VRL, first identified in 1951, generally is associated with primary central nervous system lymphoma (PCNSL), which usually is a high-grade B-cell lymphoma that remains confined to the CNS.

“Intraocular involvement occurs in about one quarter of those with PCNSL; however, in about 85% of VRL, PCNSL is present,” said Dr. Pe’er, past head, Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusale. In addition, a diagnosis of VRL can become evident before, at the time of, or years after CNS lymphoma develops.

Diagnosing VRL
The disease is characterized by the presence of clumps or sheets of vitreal cells and in about a third of the patients also by yellow-white subretinal infiltrates seen during clinical examinations. Dr. Pe’er pointed out that these cells often can be misdiagnosed as nonresponsive uveitis.

Laboratory evaluation is by far the most decisive method of diagnosis, based on the analysis of specimens obtained during vitrectomy.

“Cytology is the gold standard, but it often is insufficient to confirm primary intraocular lymphoma. In addition, the specimen must be tested very rapidly because of the cellular fragility,” he advised.

Gene rearrangement is another hallmark of the disease as exhibited by polymerase chain reaction (PCR) in which B-cell lymphoma shows immunoglobulin heavy-chain rearrangement (IgH) and T-cell receptor gene arrangement for T-cell lymphoma, he explained.

Cytokine analysis performed using an enzyme-linked immunosorbent assay (ELISA) can detect IL-10 and IL-6 in the vitreous; the IL-10 level is higher in lymphoma. “The objective is to determine the ratio between IL-10 and IL-6,” Dr. Pe’er said.